1. Field of the Invention
This invention relates to structures for fixing lugs to drums such as bass drums, snare drums, and marching drums, for example.
2. Description of the Related Art
In general, drums such as bass drums, snare drums, and marching drums are equipped with drumhead stretching mechanisms for supporting and stretching drumheads, to which prescribed tensions are applied. An example of a drumhead stretching mechanism (or a clamping mechanism) is disclosed in Japanese Unexamined Patent Publication No. 2002-366140.
A conventional example of a snare drum equipped with a drumhead stretching mechanism will be described with reference to FIGS. 9 and 10, wherein FIG. 9 is a perspective view showing an exterior appearance of a snare drum 16, which is vertically reversed upside down, and FIG. 10 is a cross sectional view showing a lug fixing structure for use in the snare drum 16 of FIG. 9. Specifically, reference numeral 1 designates a hollow cylinder (corresponding to a body of a snare drum) whose both ends are open, 2 designates a drumhead, 2a designates a front-side drumhead, 2b designates a backside drumhead (or a snare head), and 3 designates a drumhead stretching mechanism for supporting and stretching the drumhead 2 under tension.
The drumhead stretching mechanism 3 is constituted by a ring head frame 5 that is equipped with the outer circumference of the opening of the hollow cylinder 1 to hold outer circumferential ends of the drumhead 2, a ring clamp frame (or rim) 6 that is equipped with the outer circumference of the opening of the hollow cylinder 1, a plurality of lugs 8 that are arranged with prescribed distances therebetween and are fixed to the outer circumference of the hollow cylinder 1 by bolts 7 and nuts, and a plurality of bolts 9 that are arranged with prescribed distances therebetween and are attached to the clamp frame 6. Each of the bolts 9 is inserted through a bolt fixing hole 11 of the clamp frame 6 via a washer 12 and is engaged with a lug nut 13 of the. lug 8, so that the clamp frame 6 and the lugs 8 are interconnected together. The lug nut 13 is normally pressed towards the bolt 9 by a compression coil spring 14, so that it is pressed to the interior wall of the lug 8. In the aforementioned structure, when the bolt 9 is clamped using a tuning key (not shown) so that the clamp frame 6 is pressed to the head frame 5, the head frame 5 is moved to the lugs 8 so that the drumhead 2 is automatically expanded in a diameter direction thereof, wherein a tension applied to the drumhead 2 is increased, thus adjusting the snare drum in tone color and tone pitch. Incidentally, reference numeral 15 designates a snappy (or a snare) arranged for the backside drumhead 2b. 
In the snare drum 16 described above, the lugs 8 are fixed to the outer circumference of the hollow cylinder 1 by bolts 7, and the lug nuts 13 are firmly installed in the lugs 8 in such a way that the lug nuts 13 will not easily fall off from the lugs 8. For this reason, in order to replace the drumhead 2 with a new one, a human operator (e.g., a player or a user) should first loosen the bolts 9 to be extracted from the lug nuts 13, and then, the human operator removes the clamp frame 6 and the head frame 5 from the hollow cylinder 1. Therefore, it is very troublesome for the human operator to extract the bolts 9 from the lug nuts 13, which takes a relatively long time.
When installing a new drumhead in the hollow cylinder 1, the human operator should first attach the head frame 5 and the clamp frame 6 to the hollow cylinder 1, and then, the human operator puts the bolts 9 into the lug nuts 13 so as to operate the clamp frame 6 clamping the head frame 5. Herein, it is very troublesome for the human operator to screw the bolts 9 into the lug nuts 13.
To overcome the aforementioned drawbacks, it is possible to provide a lug nut fixing structure shown in FIG. 11, wherein a specially designed clamp member 21 constituted by a main portion 21A, hooks 21B, and a slot 21C is substituted for the aforementioned lug 8. The clamp member 21 is fixed to the outer circumference of the hollow cylinder 1 by a screw. In addition, a tapped hole 22 is formed at approximately the center of the lug nut 13 having a rod-like shape in a longitudinal direction, and it penetrates through the lug nut 13 in a diameter direction. Furthermore, the bolt 9 is put into and engaged with the tapped hole 22 of the lug nut 13, which is then engaged with the hooks 21B of the clamp member 21, so that the bolt 9 is inserted into the slot 21 C of the clamp member 21.
In the above, when the bolt 9 is rotated to be loosened so that the lug nut 13 is moved towards the tip end of the bolt 9 but does not fall off from the bolt 9, it is possible to easily take off the lug nut 13 from the hooks 21B of the clamp member 21. That is, it is possible to easily replace a drumhead with a new one without extracting the bolt 9 from the lug nut 13.
However, the aforementioned lug nut fixing structure shown in FIG. 11 suffers from a problem in that, similarly to the aforementioned lug 8 shown in FIGS. 9 and 10, a relatively large contact area is required for the clamp member 21 to be brought into contact with the outer circumference of the hollow cylinder 1 in order not to prevent the hollow cylinder 1 from vibrating during playing of a drum.
In addition, after the bolt 9 is loosened, the bolt 9 is rotatably moved in a direction A about a point at which the bolt 9 is interconnected with the clamp frame 6, so that the lug nut 13 is taken off from the hooks 21B of the clamp member 21. Thereafter, when the bolt 9 is rotatably moved backwards, the lug nut 13 is moved under the hooks 21B and thus unexpectedly hooked on the clamp member 21 again. For this reason, when the drumhead 2 is replaced with a new one, the human operator should temporarily hold the bolt 9, which is loosened and is taken off from the clamp member 21, by hand so as not to move backwards under the hooks 21B, and then, the human operator should remove the clamp frame 6 from the hollow cylinder 1. However, it is very difficult for the human operator to temporarily hold all the bolts 9, which are arranged with equal distances therebetween on the outer circumference of the hollow cylinder 1. This still indicates that there is a room for further improvement in the lug nut fixing structure of FIG. 11 similarly to the foregoing lug fixing structure shown in FIGS. 9 and 10 because it is still a nuisance to replace the drumhead 2 with a new one.